The present invention relates to the field of mass storage devices. More particularly, this invention relates to a slider for use in a disk drive which includes a ramp for loading and unloading a transducing head to and from the disk.
One of the key components of any computer system is a place to store data. Computer systems have many different places where data can be stored. One common place for storing massive amounts of data in a computer system is on a disk drive. The most basic parts of a disk drive are a disk that is rotated, an actuator that moves a transducer to various locations over the disk, and electrical circuitry that is used to write and read data to and from the disk. The disk drive also includes circuitry for encoding data so that it can be successfully retrieved and written to the disk surface. A microprocessor controls most of the operations of the disk drive as well as passing the data back to the requesting computer and taking data from a requesting computer for storing to the disk.
The transducer is typically housed within a small ceramic block. The small ceramic block is passed over the disk in a transducing relationship with the disk. The transducer can be used to read information representing data from the disk or write information representing data to the disk. When the disk is operating, the disk is usually spinning at relatively high RPM. These days common rotational speeds are 7200 RPM. Some rotational speeds are as high as 10,000 RPM. Higher rotational speeds are contemplated for the future. These high rotational speeds place the small ceramic block in high air speeds. The small ceramic block, also referred to as a slider, is usually aerodynamically designed so that it flies over the disk. The best performance of the disk drive results when the ceramic block is flown as closely to the surface of the disk as possible. Today""s small ceramic block or slider is designed to fly on a very thin layer of gas or air. In operation, the distance between the small ceramic block and the disk is very small. Currently xe2x80x9cflyxe2x80x9d heights are about 12 microinches. In some disk drives, the ceramic block does not fly on a cushion of air but rather passes through a layer of lubricant on the disk.
Information representative of data is stored on the surface of the memory disk. Disk drive systems read and write information stored on tracks on memory disks. Transducers, in the form of read/write heads, located on both sides of the memory disk, read and write information on the memory disks when the transducers are accurately positioned over one of the designated tracks on the surface of the memory disk. The transducer is also said to be moved to a target track. As the memory disk spins and the read/write head is accurately positioned above a target track, the read/write head can store data onto a track by writing information representative of data onto the memory disk. Similarly, reading data on a memory disk is accomplished by positioning the read/write head above a target track and reading the stored material on the memory disk. To write on or read from different tracks, the read/write head is moved radially across the tracks to a selected target track. The data is divided or grouped together on the tracks. In some disk drives, the tracks are a multiplicity of concentric circular tracks. In other disk drives, a continuous spiral is one track on one side of a disk drive. Servo feedback information is used to accurately locate the transducer. The actuator assembly is moved to the required position and held very accurately during a read or write operation using the servo information.
Disk drives have actuator assemblies which are used to position the slider and transducer at desired positions with respect to the disk. The slider is attached to the arm of the actuator assembly. A cantilevered spring, known as a load spring, is typically attached to the actuator arm of a disk drive. The slider is attached to the other end of the load spring. A flexure is attached to the load spring and to the slider. The flexure allows the slider to pitch and roll so that the slider can accommodate various differences in tolerance and remain in close proximity to the disk. The slider has an air-bearing surface (xe2x80x9cABSxe2x80x9d) which includes rails and a cavity between the rails. The air-bearing surface is that portion of the slider that is nearest the disk as the disk drive is operating. When the disk rotates, air is dragged between the rails and the disk surface causing pressure, which forces the head away from the disk. At the same time, the air rushing past the depression in the air-bearing surface produces a negative pressure area at the depression. The negative pressure or suction counteracts the pressure produced at the rails. The different forces produced counteract and ultimately fly over the surface of the disk at a particular fly height. The fly height is the thickness of the air lubrication film or the distance between the disk surface and the head. This film eliminates the friction and resulting wear that would occur if the transducing head and disk were in mechanical contact during disk rotation.
One of the most critical times during the operation of a disk drive is just before the disk drive shuts down. The small ceramic block is typically flying over the disk at a very low height when shutdown occurs. In the past, the small block was moved to a non data area of the disk where it literally landed and skidded to a stop. Disk drives that park the slider on a non data area of the disks have problems. One of the problems is the result of using disks with a smooth surface within the disk drive. When the sliders are parked on the smooth surface of the disk, stiction results between the slider, a small ceramic block, and the disk surface. In some instances, the force due to stiction are large enough to virtually rip the slider away from the load spring. Other problems include the limited life of the disk drive. Each time the drive was turned off another start stop contact cycle would result. After many start stop contacts, the small ceramic block may chip or produce particles. The particles could eventually cause the disk drive to fail.
To overcome the problems associated with parking a slider on the disk, ramps where added to disk drives so that the sliders could be removed from the disk surface before landing. Adding ramps eliminates the problems of stiction and particle generation from landing the slider on the disk surface. In most designs, a ramp is placed on the edge of the disk. A portion of the ramp is positioned over the disk itself. The power down procedure includes moving the load springs and attached sliders to the ramp where a portion of the load spring or an attached tang rides up the ramp to controllably remove the slider or sliders from their respective disk surfaces. Of course, with the sliders or ceramic blocks positioned on the ramp, the sliders do not contact the disk. Commonly, this procedure is referred to as unloading the heads. Unloading the heads helps to insure that data on the disk is preserved since, at times, unwanted contact between the slider and the disk results in data loss on the disk. When a disk drive is started, the load springs and sliders are moved down the ramp to place the sliders over the disk surface. This procedure is commonly referred to as loading the heads onto the disk. Disk drives with ramps are well known in the art. U.S. Pat. No. 4,933,785 issued to Morehouse et al. is one such design. Other disk drive designs having ramps therein are shown in U.S. Pat. No. 5,455,723, U.S. Pat. No. 5,235,482, and U.S. Pat. No. 5,034,837.
As the load spring or tang rides up and down the ramp surface during a loading or unloading operation, the slider rotates on its longitudinal axis. Another way of saying this is that the slider will roll when it goes up or comes off of the ramp. Since the slider is located so closely to the disk, when the slider rolls during loading or unloading, many times the slider contacts the disk. When the slider contacts the disk, the disk or the slider may become damaged and expose the disk drive to an immediate or eventual head crash in which all or some of the data could be permanently lost.
Typically the corners or edges of the slider are the portion of the slider that contacts the disk during loading or unloading operations. In some disk drives, the corners of the slider are rounded or blended so that the damage produced by disk contact is minimized. There are several problems with this approach. The slider with blended or rounded edges does not absorb any shock. Although the force of the shock is dispersed over a larger area, contact between the disk and slider still occurs. The potential for loss of data and the potential head crash remains even though the corners and edges of the slider have been rounded or blended. Another drawback is that the flying characteristics are changed when the surfaces of the slider are blended or rounded. Blending or rounding of the edges and corners change the aerodynamics of the sliders. Blending adds many unknowns, for example, to the predictions used for fly height of the slider. In addition, blending or rounding also adds to the complexity of manufacture of the sliders.
As can be seen, there is a need for a slider that can absorb some of the impact that might occur when the slider contacts the disk during a loading or unloading operation. There is also a need for a solution which will not change the aerodynamics and is still relatively easy to manufacture. There is also a need for a solution which will not generate particles and put the disk drive at risk of a disk crash.
A disk drive system includes a base, a disk stack rotatably attached to the base, and an actuator assembly movably attached to the base. A ramp assembly includes a set of ramps for loading and unloading the sliders and transducing elements carried by the sliders to and from the disks in the disk stack. The ramp assembly is attached to the base. An actuator assembly is movably attached to the base of the disk drive. The actuator assembly includes one or more arms. A load spring is attached to the at least one arm of the actuator. In some instances two load springs are attached to the arm of the actuator. A slider is attached to the load spring. The slider includes a block of material having corners and edges. Sliders have a backside surface and an air-bearing surface. The slider has a recess therein.
A pad of shock absorbing material is positioned within the recess. A transducer element is attached to said slider. The pad is positioned within the recess of the slider to prevent contact with the corners or edges of the block of material with another surface, such as the disk. The block of material also may include a plurality of recesses therein. A plurality of pads of shock absorbing material are positioned within at least some of the recesses in the slider. The pads are positioned within said plurality of recesses to prevent the corners or edges of the block of material near the air-bearing surface from contacting another surface, such as the disk drive. The pads include a first shock absorbing material, and a second material harder than the shock absorbing material. In one embodiment, the pads are positioned within the recesses so that the second material is positioned near the air-bearing surface. The second material can be diamond like carbon. After forming the pad, diamond like carbon is deposited on the pad using photolithography.
Advantageously, the slider with the capped elastomeric pads can absorb some of the impact that might occur when the slider contacts the disk during a loading or unloading operation. Since the pads are placed in recesses on the slider the aerodynamics do not change appreciably. The same aerodynamic predictors can be used by designers. In addition the slider is still relatively easy to manufacture. In addition, the slider with capped polymeric pads will absorb some of the impact shock and will lessen the possibility of particle generation and will lessen the risk of a head crash in the disk drive, when compared to other previously tried solutions.